Essaouira is known as the city of wind although I would call it the city of cats. It is a costal town famous for the nice local mix European architecture not as chaotic as Marrakech or Fes as well as its very chill vibes. Great place to take it easy and not be harass by vendors.
Casablanca or just Casa is not a place you want to visit if you can avoid it. It is not particularly pretty and has nothing that can be call a must-see. It is just the economic center of the country. Many travelers end up here because of the flights but if you have the chance to flight straight to Marrakech I would recommend it. People spending 24 hours here can kill some time with the following attractions.